Re: Undefined behaviour [was Re: The D Programming Language]
David Abrahams wrote:
"Andrei Alexandrescu (See Website For Email)"
<SeeWebsiteForEmail@erdani.org> writes:
Having a bunch of other boxes means tools like Purify and Valgrind
get a whack at detection.
I understand the point, but I think it's not strong. A program with
errors in just one box has the opportunity to test itself.
Earlier in my career I used to write *lots* of ASSERTs. That phase
turned out to be hugely important for my development as a programmer.
As I've improved, though, I've find ways of enforcing more guarantees
about my programs with the type system, and consequently
"self-testing" has lost a great deal of value for me. I still do it
here and there, but it's much rarer in my code than it used to be.
There's little point in writing ASSERTs for the truth that stares you
in the face -- they just clutter up your code.
Of course I agree with that. My one-liner about assertions is that "with
a perfect compiler, you wouldn't need assert". It has been shown,
however, that verifying statically something as simple as "this array
stays sorted throughout the program" is prohibitively expensive with
what technology we currently have. So, I do end up using quite a few
assertions in my code.
In fact, I've come to
distrust anything that smells like "looking over my own shoulder to
make sure that everything's still OK," as it slows programming down
and quickly becomes a maintenance and comprehensibility liability.
I guess I'm more liberal with sprinkling assertions, particularly
because code has this property - local change causes nonlocal effects.
But, not a biggie.
A program with errors in various boxes lacks that opportunity, which
opens the door for tools to come in and do that.
Or it gives the tools the opportunity to do it. Personally I'd rather
have the opportunity to automate than the "opportunity" to check
manually.
Nice try to turn the table :o).
Andrei
--
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]